1. Field of the Invention
The invention relates to the prevention of intraoral and tooth trauma.
2. State of the Art
Facial trauma experienced by athletes has been demonstrably reduced by the use of a mouth guard during participation in athletic events. These mouth guards, or mouth protectors, provide protection against injuries to the teeth, lips, cheeks, and gums, and may also reduce the incidence of head and neck injuries, concussions, and jaw fractures.
A number of mouth guards currently exist in the art for protecting against the injuries described above. The American Society for Testing and Materials has classified mouth guards into three types: stock mouth guards, mouth-formed mouth guards, and custom-fabricated mouth guards. Some of these mouth guards are fitted with a tether or strap to connect them to a fastening point, such as a helmet or the like, to prevent loss, swallowing, or choking on the mouth guard by the user. Generally, mouth protectors are fabricated to cover all teeth of the maxillary arch, except for the erupting third molars. To provide maximum protection, it is believed that the energy absorbed by the mouth protector must be dissipated by the protector, rather than transferred to the underlying tooth and jaw structure.
Stock mouth guards typically can be purchased at sporting goods stores, department stores, and pharmacies. These mouth guards may be made of rubber, polyvinyl chloride, or polyvinyl acetate copolymer and are typically available in small, medium, and large sizes. These stock mouth guards are not in any way molded or “fit” to the persons wearing them and, as a result, can be loose and uncomfortable for the user. Often the mouth must be closed in order to hold them in place, and many athletes find them bulky and uncomfortable. In addition, these mouth guards can interfere with speech and breathing, which is a further strong disincentive for athletes to wear these mouth guards.
Mouth-formed mouth guards are fitted by the user. They are molded to fit the individual wearer either by the use of a moldable inner liner typically of plasticized acrylic gel or silicone rubber, or the use of a moldable thermoplastic that softens when immersed in boiling water and re-hardens when cooled. The thermoplastic mouth guard is also known as the “boil-and-bite” mouth guard. However, repeated biting during participation in athletic events or gnawing due to nervousness before or during an athletic event can cause the material to spread resulting in a loose fit. In addition, aging and/or continual exposure to oral fluids may cause the plasticizers to leach out causing the liner to become hard. The method of forming these mouth guards can also be uncomfortable and difficult for a user to perform. Namely, the user is required to boil the guard for the prescribed amount of time and then insert the hot material into the user's mouth and bite down on it, which can be very uncomfortable. The quality of these mouth guards is clearly highly user-dependant.
Cook, U.S. patent application No. 2002/0144686, describes a “soft” boil-and-bite type of mouth guard. Instead of being made of the traditional ethylene/vinyl acetate (EVA) polymer, it is made of a soft impressionable low-density polyethylene. Wagner, U.S. Pat. No. 5,566,684, describes a mouth guard made of a low softening temperature thermoplastic (e.g., EVA) liner on top of a higher temperature thermoplastic. It is described as a do-it-yourself mouth guard that is formable by the boil-and-bite technique. These mouth guards still suffer from the same disadvantages of traditional boil-and-bite guards.
Another mouth-formed guard is made in a dentist's office by impressing the teeth directly onto an uncured ethyl methacrylate gel, which is laid into an outer mouth guard shell/tray all of which becomes one device. Although the custom fit of the softer “lining” feels more comfortable, some users object to its taste and odor. Instructions for the use of these guards advise that the lining be replaced before every use, and that the actual fitting be done by a dentist, hence, increasing the cost of the guard.
Custom-made mouth guards are considered to be the best of the conventional mouth guards as far as fit, shape retention, and comfort are concerned, but they are also the most expensive. This type of mouth guard tends to be less bulky than the other two types and may stay in position better. Custom mouth guards are typically composed of a thermoplastic polymer, of which the most popular type is ethylene/vinyl acetate copolymer, although acrylic resin, polyurethane, and various rubber materials are also used. Custom-made mouth guards are fabricated by vacuum-drawing a thick thermoplastic film/sheet over a dental mold formed by standard dental impression techniques, and most often this process is done by a dentist or in a dental laboratory. There are usually four steps required in the making of a custom-fit mouth guard: 1) making an impression of the maxillary arch; 2) pouring a cast; 3) forming the thermoplastic material on the cast; and 4) finishing the protector. Because of the special technique used in the dental office, the guards are rather expensive, and still slightly uncomfortable due to the rigidity of the thermoplastic used. Although these mouth guards are reusable, they cannot, ordinarily, be fabricated in the field.
The mouth guards described above are typically U-shaped to match the general shape of the upper dental arch and have upward inner lingual and outer labial walls extending therefrom. Bi-maxillary mouth guards are also available which have protection for both dental arches and hold the mouth in a pre-determined position to allow for maximum breathing capability.
Jones et al., U.S. Pat. No. 5,746,221, teaches a mouth guard made of polytetrafluroethylene or PTFE. The PTFE is cold formable thus it will mold to a user's teeth without being heated. However, the mouth guards of Jones et al. do not cure but remain soft and are easily deformed during use. In fact, Jones et al. teaches the mouth guards are “extremely resistant to hardening” (see col. 6, lines 46-48). A user's teeth and gums directly contact the mouth guard material which the user may find unpleasant and foul tasting.
Going et al., U.S. Pat. No. 4,063,552, teaches a silicone based mouth guard. The mouth guard is formed by squeezing a polydimethyl siloxane material from a packet into a cylindrically shaped dough. The silicone dough is then placed on a U-shaped tray. A user inserts the tray into the mouth and pushes the silicone dough upward to engage the upper teeth. The tray is then removed and the silicone is held in the mouth allowing it to cure. However, significant problems are encountered because the silicone is applied directly to the user's teeth and gums. Firstly, the silicone is forced out above the upper tray edges by the teeth and gums. This material must be reapplied to, for example, along the outside gum surfaces by smoothing it out with the index finger. Also, excess material must be removed. Secondly, the silicone substantially sticks to the tray making it very difficult to remove the tray from within the mouth. To remedy this, Going et al. teach a complex two-part tray equipped with a release liner. Thirdly, undesired chemicals may be absorbed by the user's gums or mucosa due to the direct contact with the uncured silicone, which could lead to skin lesions and rashes in the mouth. The user may also find direct contact with the silicone paste (or putty) unpleasant, foul tasting, and unhygienic.
Fischer et al., U.S. patent application No. 2003/0145863, describes a method of adding an extra cushioning layer to an existing mouth guard by dispensing a curable elastomeric material into the trough of the mouth guard. The device is then placed into a person's mouth to impress the teeth into the material and allowing it to cure, at least partially while inside of the mouth. Fischer et al. discloses that a polysiloxane can be used as the curable elastomeric material. This method suffers from many of the same disadvantages as that of Going et al. Namely, there is direct contact between the user's teeth and gums and the mouth guard material; and the extra cushioning layer material is not prevented from oozing out over the walls surrounding the trough of the mouth guard.
Adell, U.S. Pat. No. 4,955,393, teaches a mouth guard comprising a teeth impressionable liner. The liner can be made of urethanes, silicones, or vinyls and is less rigid than a trough material. A user bites down on the liner, which begins to cure due to the water in a user's saliva. The user then removes the mouth guard and places it in water to complete the curing process. This mouth guard suffers from the same problem of direct contact between the user's teeth and gums and the mouth guard material.
Adell, U.S. Pat. No. 5,406,963, teaches a similar mouth guard and its method of manufacture. This mouth guard comprises a main body and a tooth impressionable liner made of substantially the same material. The materials of the two parts differ only in durometer with the durometer of the main body material being higher than that of the liner material. This mouth guard still suffers from unpleasant direct contact between the user's teeth and gums and the uncured mouth guard material.
Monaghan, U.S. Pat. No. 3,224,443, teaches a method of forming a mouth guard comprising applying a fiber filled silicone putty directly to a user's teeth. The user then works the putty around the teeth using their fingers and tongue and then bites down on the putty to form tooth impressions. The thus formed guard then cures in the mouth. Clearly, a mouth guard formed by this method is prone to thickness differentials and non-uniformities that could lead to injury while in use. Of course, this method also suffers from the problem of direct contact between the silicone putty and the user's teeth and gums which in the extreme could include swallowing and absorbing hazardous curing agents through the gums or mucosa of the user.
Fishman et al., U.S. Pat. No. 5,816,255, describes forming a mouth guard by a similar method except that a bite bar is utilized to hold the putty. A user first measures out equal amounts of a base putty and a catalyst putty. The user then mixes the putty together to form a curable putty. The user then rolls the curable putty into a cylindrically shaped mass and then curves the putty around the bite bar to form a generally U-shaped putty. The putty is then inserted into the user's mouth and the user bites down on the putty and allows it to cure. This mouth guard suffers from the same non-uniformities and direct contact problems as that taught by Monaghan. The method also suffers from relying on the user to perform the cumbersome task of measuring equal amounts of the two putty. Thus, the method is time consuming, frustrating, and the quality of the finished mouth guard is highly user-dependant.
There remains a need for a high quality mouth guard that is relatively inexpensive and readily user-formable. Specifically, there is a need for a user-formable mouth guard that does not require direct contact between the user's teeth and gums, and the uncured mouth guard material.